1. Field of Invention
The present invention relates to a circuit, and more particularly to a scan-type display device control circuit.
2. Related Art
In recent years, the cost of manufacturing light-emitting diodes (LEDs) is greatly reduced. Therefore, LED displays have been widely applied in various occasions, such as gymnasiums and billboards.
Usually, an LED display device uses thousands of LEDs as displaying pixels. A frame may be constituted by pixels having different brightness, and multiple frames may be displayed in sequence to constitute a dynamic image.
The pixels are controlled by a controller respectively. According to input data, the controller transmits an ON signal or an OFF signal to an LED driver, thereby controlling the brightness of the pixels.
Generally speaking, the dynamic image will switch about 60 frames every second. That is to say, a frame rate of the input frames is 60 Hz. Since the period of switching the frames is very short, when watching the progressive image, people will feel that the progressive image is continuous due to the visual staying phenomenon.
Furthermore, the time for displaying a whole frame is referred to as a refresh time. The inverse number of the refresh time is a refresh rate. The higher the refresh rate is, the more difficulty the LED display device flickers (for example, when taking a photo by using a high-speed shutter of a photography appliance).
In another aspect, quite a number of LED drivers are required in a common LED display device. In order to reduce the number of the LED drivers, the LED display device can adopt a scan-type controller. In the scan-type controller, multiple LEDs may be driven in different time by a switching device. Therefore, the same one LED driver may drive multiple LEDs.
Although the scan-type controller can save the number of LED drivers, for the same LED driver, the data quantity to be processed is multiplicative. That is to say, the LED driver needs a larger transmission band width. Furthermore, since more time will be spent for displaying a whole frame, the refresh rate will descend accordingly.